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[Yaesu] FT990 Receiving Antenna

To: <yaesu@contesting.com>
Subject: [Yaesu] FT990 Receiving Antenna
From: heyer@nortel.ca (Friedemann Heyer)
Date: 04 Nov 1997 07:28 EST
Hallo All,

Comming across the Receiving Antenna problem found in the mail of Oct. 08th.,

I want to mention that I have the same problem with my FT990.

I have an under-the-roof dipol and a separate receiving antenna from outside the
house to a near-by tree. The coax feed lines of both antennas are going from 
under
the roof close together to the ground floor into the shack.

During transmitting and having selected the separate receiving antenna,
RF is fed back into the 990 which can lead so far, that the internal 
power-supply
or the tuner oscillates and the supply voltage is breaking down,
which can be seen because the S-meter lamp becomes dark and darker ...

There is also a surge supressor on the RF-board but besides that there is no
disconnecting of the rec. ant. while transmitting as far as I see it.

The FT990 is still working :-) ,
but I can't use the separate rec. ant. while transmitting

I wonder if anybody has come across this problem with a 990.
Any reply is very much appreciated.


73, 
Friedemann, DF2GX

friedemann.heyer@nortel.ca



In message "[Yaesu] FT1000MP Receiving Antenna", nt5c@easy.com writes:

> A question for FT1000MP owners (I'm thinking of joining that fine group):
> 
> When a separate RX antenna is selected by the front panel switch, it seems
> from Yaesu's "Technical Overview" document that the RX antenna remains
> connected to the receiver front end even during transmit. If the RX antenna
> is a long Beverage for example, that could put a considerable voltage into
> the receiver front end. The Overview does say "A surge supressor is is
> included on the antenna input line....", but nothing more. (It's impossible
> for me to see how things are supposed to work in the condensed, illegible
> front end schematic). I'm surprised they didn't disconnect the RX antenna
> line during transmit, with appropriate grounding.
> 
> Should one do something externally about this, or isn't there a problem?
> The folks I've asked individually seem to say don't worry about it. With
> close to $3K on the line, I'd prefer to worry!!!
> 
> Thanks,
> John, NT5C.
> 
> 
> 
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